Abundance
by CaraWinter
Summary: Mycroft doesn't think her little brother is ready to stop breastfeeding, but Mummy thinks he should be weaned. She takes matters into her own hands and slowly but surely, Sherlock becomes hers.
1. Chapter 1

The first time it happens, Mycroft is eight. She hears her mother saying to a friend that Sherlock is quite old enough to be weaned, but doesn't seem to want to give up the breast quite yet, and then she frowns, because when she'd got a baby brother she'd looked in to these things and she remembered that the World Health Organisation had said children should be breastfed until at least the age of two. She doesn't want Sherlock to be deprived. She slips away from the garden party and goes up to the nursery, smiles at the eager welcome from the cherub standing in his crib and rattling the bars. He is always pleased to see her. She stands on a box and lifts him out of the crib, carries him to the rocking chair, and cradles him in her lap while she lifts her shirt. The baby nuzzles closer, latches on to her nipple automatically, clinging to her. He doesn't get any milk, but he doesn't mind, because it's nice, to be cuddled like this, allowed to suckle. Mycroft likes it too. She lets him suckle her for half an hour, switching breasts half way through, until he falls asleep with her nipple in his mouth.

She takes to visiting him twice a day, once in the morning and once at night, alternating the breast she allows him to suckle. Her breasts are barely developed, hardly more than buds, but Sherlock doesn't care. He likes being petted and cuddled by his big sister while he suckles her.

* * *

><p>By her ninth birthday, they've established a rhythm, and Sherlock fusses and whines if they miss a session. She coos to him softly and strokes his curls the next time, lets him suckle a little longer, and he rests his tiny fist on her other breast as he snuffles and pushes closer, his little jaw working as he sucks. He can walk now, and climb up onto chairs, and their parents smile fondly as he toddles to Mycroft the moment she enters any room, climbing into her lap, wanting to be held and petted. It doesn't occur to them that he'd like to be cuddled by them too.<p>

She tells herself she'll stop when Sherlock stops wanting it. She tries to bring it up a few times, but his little bottom lip wobbles and he looks at her with big sad eyes and she can never go through with it. He grows, becomes boisterous and destructive, and only Mycroft can get him to calm down. "Come here Lockie," she says softly, encouragingly, and he becomes meek and allows himself to be led by the hand to somewhere private he can nurse from her. She never calls him Lockie at any other time.

* * *

><p>A little after her tenth birthday, when she has been suckling Sherlock for nearly two years, she hears a surprised little grunt as he nurses. It's not unusual for him to vocalise as he suckles, he makes tiny soft noises of contentment most of the time, but this sounds different. "What is it Lockie?" she asks gently, brushing the curls off his forehead. "Milk," he replies curtly, latching back on and suckling enthusiastically, kneading her small pert breasts with his little fists like a kitten against its mother. She gasps quietly, and cradles him, allowing him to feed from her. She likes the slightly prickly feeling in her nipples as he draws her milk out, she likes how happy her little brother is curled up in her lap, calm and loved. He suckles until the milk is finished and shuffles across to the other breast, closing his little lips around her nipple and sucking gently, humming as Mycroft strokes his hair and he swallows all the milk she can give him.<p>

They indulge every morning and every night, and sometimes Sherlock comes to her to request it. He is allowed extra on his birthday and at Christmas, and gradually her milk grows thicker, creamier, her breasts swell with it and she has to buy nursing pads to stop herself from leaking when she hasn't nursed him in a while. It becomes a nightly ritual for them, Sherlock climbing into her lap and snuggling against her, happily feeding from her bare breasts as she pets him and croons to him, telling him what a good boy he is and how much she loves him.

Somehow, it never stops. Sherlock likes her milk, likes the intimacy and attention, and Mycroft cannot bear to say no to him, even when she grows older and understands the implications. When she is thirteen she tells him that they can stop whenever they like, and Sherlock whines and clings to her. He knocks on her door that night, half an hour before their usual time together, and clutches the hem of his pyjama top as he asks "Can I? Please?" in a tiny voice, peeping up at her through his eyelashes. "I don't want to stop, Mycie." She exhales and scoops him into her arms, sitting up against the headboard and lifting her top to expose her breasts, holding him to her. "We won't stop until you want to," she reassures him, even though he is six, even though he has started school.

If he's been good, she allows him an extra feed a day, just after he gets home from school. He behaves better if he knows he will be allowed to suckle from her. When he grows older, and the other children realise he's different, he starts to come home from school in tears, feeling rejected, believing their label of _Freak_. He clings to Mycroft and sobs into her blouse, and she hushes him gently,

Sherlock nurses from her long after he stops needing it. He simply wants it, he enjoys being given the only access to his sister's breasts, likes that her milk is all for him. He knows it is abnormal. He doesn't care. He outgrows her lap, slowly but surely, until one day he is all of eleven and Mycroft is eighteen. She comes home from nights out smelling of cigarettes and sweat and alcohol and men's cologne, and Sherlock grows surly and moody when she is gone, but she soothes him when she gets home. "Come here, Lockie," she offers gently, unbuttoning her blouse, and he regards her warily, until he sees that her breasts are swollen and full and untouched. He relaxes then, and takes his time nursing from her.

He realises when he is fourteen that he cannot have this forever. One day, probably soon, it will have to stop. He begins to act out again, calm only when he is on her breast and she is running fingers through his hair and cooing to him. It's what gives him his first wet dream. He grows unreasonably aroused by the thought of suckling his sister's breasts, how she opens her shirt for him and allows him to rub and suck them, her nipples plump and stiff in his mouth. Of course she notices his erection when he's nursing. She says nothing, but rubs his stomach gently. One day the pressure in his trousers becomes unbearable when he is halfway through one breast and he has to rub a hand over his aching crotch. Mycroft croons softly, replacing his hand with her own. "Let me take care of you," she whispers tenderly, the words nearly making him come in his pants. She unzips him and rubs him through his boxers as he continues to suckle, crooning to him. "That's my good boy. " It is over embarrassingly quickly. She kisses his forehead proudly and cleans him off with tissues as he finishes nursing.

* * *

><p>They begin to share a bed, unbeknownst to their parents, so they can nurse last thing at night and first thing in the morning. They snuggle together under the blankets, limbs tangled, as Sherlock pushes up her nightie and nuzzles her breasts, rubbing and licking her nipples before latching on.<p>

One day when Sherlock is fifteen, he finds his thigh between Mycroft's legs as he suckles, his erection pressing against her. He rocks his hips, gradually working his way on top of her. He is big for his age, and just as tall as she is; he is wiry but strong, his curls wild and his voice deep. Mycroft knows he is attractive. "I want you, Mycie," he whispers hotly, his thick cock pressing against her knickers. "Please." She strokes his cheek, opens her mouth to speak, but closes it again after seeing the lust and need in his eyes. She smiles and spreads her legs, lets him remove her pants, wraps her arms around his waist as he positions himself on top of her and moans softly as he pushes his cock inside her. He shudders at her tight wet heat, thrusting eagerly and clumsily, panting against her neck. In just a few minutes, he cries out into the pillows as he spills deep inside her. "I love you Mycie," he whispers, hiding his face against her collarbone. She pulls him up to look at her, his softening cock still inside her, and kisses him tenderly on the lips. "I love you too, Lockie," she says earnestly. He exhales sharply and kisses her again, growing hard at the sensation, and thrusts into her gently, spurred on by her quiet encouragements, moaning when she wraps her legs around his waist. He touches her breasts as he fucks her, making her gasp and moan. He always was a quick learner. He thrusts in as hard as he can when he cums inside her again.

It becomes part of their routine. He nurses first, eagerly suckling her milk from her swollen breasts, and then they make love, Sherlock marking his possession of her by cumming in her. He never tells her that she is his. He doesn't think he needs to.

* * *

><p>When she moves to London, he turns to drugs. Their parents hide it from her. She has to buy a breast pump to relieve the ache in her breasts. She tries to call him, she sends their parents a key to her flat to give Sherlock, but he refuses to talk to her. His parents force him to go to rehab, and finally call her. She turns up on his sixth day in the centre, when he is weak and shaking, her eyes red from crying. He whimpers when he sees her, and turns away, ashamed. An arch eyebrow sent the staff from the room and she sat on the bed, gazing at him, her heart breaking. "Come here, Lockie," she whispers, opening her arms. He snaps his eyes up, lower lip trembling, and flies to her, throwing his arms around his neck. "I'm sorry, Lockie," she says shakily into his hair. "I'll never leave you again." He sobs against her blouse until he is calm, and unbuttons her with shaking hands, latching on with a whimper and nursing desperately, clinging to her as she redeems him with her milk.<p>

She takes him to London with her when he leaves rehab. They find their old rhythm again, sharing a bed, snuggling quietly together as Sherlock suckles. She tests him regularly for illicit substances, telling him if he fails she won't allow him to nurse for a week. He never fails.

He finds consulting detective work and she becomes the British Government. Their sexual relationship expands outside of nursing, and he fucks her bent over the kitchen table or up against the wall in the shower. He loves cumming inside her, filling her with his seed; it becomes his new drug of choice. Mycroft has no objections. "You know what this means, don't you," he growls one day, pounding her into the mattress, watching her breasts bounce with each thrust. "Me fucking you like this, filling you with my cum. You're mine." She nods breathlessly in agreement, pulsing around him, and he fills her again.

When he decides he wants to take his possession of her further, he whispers in her ear as he's fucking her over the arm of the sofa that he wants her to carry his baby, to grow round and ripe with a dark-haired baby he put inside her. She gasps as her orgasm hits her. She doesn't go off her birth control right away, she's too clever for that; she has him give her sperm samples "for genetic testing" and arranges for embryos to be created using his sperm and her eggs. She selects two for implantation that are genetically healthy while Sherlock is away for six weeks on a case; one implants. When he comes back, she pulls him into the bedroom by his lapels and tells him to give her a baby right then and there, and Sherlock grins and tackles her onto the bed, fucking her with enthusiasm. He knows what's really going on, of course, but that doesn't make the game less fun.

Sherlock is thrilled when Mycroft confirms her pregnancy, kissing her heatedly on the lips. He watches as his sister grows heavy and round with his child, her ripe belly pushing out in front of her, the knowledge that it is his baby inside her arousing him almost unbearably. He worships her growing belly at every chance he gets, whispering sweet filthy nothings in her ear; "What must they think of you? So obviously pregnant, but without a husband or boyfriend… what would they think of you if they knew the baby you're carrying is your brother's?" She doesn't answer, only shivers lightly and presses into his touch.

Her milk becomes creamier as the birth approaches, and Sherlock loves it. He gains four pounds because he feeds from her so often, his gaunt look replaced by plumper cheeks. Mycroft cradles him as he suckles, just like always, and pets his hair. Sherlock curls in closer, wrapping his arms around her, humming softly as he feels their baby kick.

* * *

><p>Mycroft gives birth to their son at a private hospital in Switzerland where nobody knows them, and Sherlock is there to hold her hand through all of it, to cut the cord and kiss her full on the mouth in his joy. When they can finally take him to their rented chalet he sits up against the headboard and holds them both against his chest as Mycroft feeds him, their tiny baby boy with dark curls and his mother's complexion. They name him Leopold Fitzwilliam Holmes, and they both adore him more powerfully than either of them thought possible.<p>

When he is bathed and dried and snug in his soft fleecy sleepsuit, Mycroft croons to him as she feeds, the baby on one breast and Sherlock suckling happily on the other. She kisses both of their foreheads, smiling as her boys snuggle closer. This is how it was meant to be, she thinks, whatever we were to each other Sherlock has always been mine and I have always been his. The small, forlorn creature rattling the bars of his cot and pleading silently to be held and loved and petted had always held her heart, one way or another, and now their love had made another tiny person, who would never want for affection. She smiled and rested her cheek in Sherlock's curls, watching as their baby blinked up at both of them.


	2. Chapter 2

Sherlock's earliest memory is of being held, a smooth cool hand stroking his hair as he suckles. The rocking chair creaks as they sway back and forth, the white voile curtains of the nursery flutter in the early summer breeze, and the scent of beeswax from the polished floorboards surrounds him; but nothing comforts him as much as this, this warm safe embrace, having arms encircling him as he is firmly latched onto the breast. His suckling is insistent but languid - he knows he can take his time. He snuffles and sighs. This is surely what it means to be loved, he thinks. "Time to switch sides now, Lockie," his sister croons softly. He releases her nipple with a small slurp and relaxes in her embrace as she bares her other breast for him.

* * *

><p>He doesn't remember the first time he tasted Mycroft's milk. He only knows that he always wanted as much of it as he was allowed. When he was four, and her milk had come in properly, he once climbed into her lap at a garden party and whispered in her ear to ask for it; Mycroft had melted and made some excuse to her parents, who were only glad she was taking Sherlock off their hands, and had marched off with him to the nursery.<p>

Sherlock clung to her as she eased into their usual chair and cooed happily as she bared both her breasts at once. "Which one do you want first, Lockie my love?" Mycroft had asked, and he had answered her by curling up against her and wrapping his little mouth around her right nipple. He suckled her gently, his eyes sliding closed as he grew drowsy, lulled by her soft body and the motion of the chair and the warmth. The milk is thick and creamy and he adores it, adores Mycroft for letting him have it, loves the knowledge that it is there for him when he wants it and that his sister will cuddle him and pet him just like she's doing now. "Good boy, Lockie... that's my sweet little Sherlock, drinking up his milk. Tastes good, hmm?" Sherlock blinked up at her and nodded, latching on to every word of praise just as firmly as he was latched to her body. Mycroft smiled and kissed his forehead, listening to the wet, tiny noises of his suckling, each small swallow as he fed on her milk. "Love you, Lockie."

"Love you too," he mumbled sweetly as he finally released the first breast. "Can I have the other one, Mummy?"

Mycroft inhaled a quiet gasp. "Lockie, you know I'm not your mother," she reminded him gently. "I'm your sister."

"I know," he muttered, frowning, "but our real Mummy doesn't cuddle me or give me milk or read me stories. You do that. I want _you_ to be my Mummy."

Sherlock didn't understand the expression on Mycroft's face, but he understood the soft kiss to his cheek and the gentle hands that guided him to her left breast. "Alright, Sherlock, I'll be your Mummy," she promised in a whisper, "but it has to be our secret. You can only call me Mummy when we're alone, okay?"

He nodded, his little fingers flexing on the hem of her blouse as he began to drink from her again.

* * *

><p>By the time he was six, Sherlock had come to associate Mycroft with warmth, love, and the delicious milk she allowed him to suckle from her. His real mother he associated with genteel neglect, indifference, and the faint smell of gin. Neither of them minded that it was always Mycroft he went to first when he got home from school; he'd bundle into her bedroom, fizzing with energy and wanting to tell her all about his day and the fascinating experiments he'd done with a dead frog he'd found by the pond, and Mycroft would smile and hold him in her lap, listening and making the appropriate noises, until he'd talked himself out of breath. He'd sigh, lay his head on the pillow of her breasts and snuggle into her, holding her tight. "I missed you, Mummy," he'd whisper, gazing up at her and hoping to hear those magic words back; "Mummy missed you too, my darling Lockie."<p>

* * *

><p>When Sherlock is eight, he begins to notice changes in Mycroft during their nursing sessions. Her milk is just as sweet and plentiful as ever, and his hunger for it remains undiminished, but she seems to react differently to his mouth on her. He catalogues her reactions to different stimuli carefully; he suckles more noisily than usual and her breathing comes just a little faster, he whines that her milk tastes <em>so good<em> and watches her pupils dilate. When he cuddles up in her lap after he has finished nursing, and whispers sweetly "I love your milk, Mummy," Mycroft lets out a soft moan and kisses his forehead. Sherlock doesn't know what this means, but he loves his Mummy, and as long as she will let him suckle her breasts he is happy.

* * *

><p>"I don't remember a time before we had this," Sherlock murmurs one day as he is taking a short break from nursing. Ten years old, he has emptied one of his sister's breasts and is waiting for the tightness in his belly to lessen before he drinks from the other. He always wants all of her milk, and today is no exception.<p>

"Really?" Mycroft replies, stroking his curls. "I suppose you were very young when we started. You were just a year old and I let you suckle me because Mother said she was going to stop, even though you weren't ready to give up the breast. I didn't want you to be without something you still needed."

Sherlock beamed at her. "I've got you," he sighed, "I'll always have what I need. You won't make me stop, will you Mycie?" He has all but grown out of his habit of calling her Mummy, now, although sometimes if he's feeling vulnerable he likes to use it.

"No, Lockie, I won't make you stop, not ever" Mycroft promises, her heart breaking a little that he still needs the reassurance. "My milk is yours as long as you want it. Open up now, there's a good boy." Sherlock obediently latches on and begins to suck, humming in appreciation at the taste of her.

* * *

><p>The first time Mycroft goes clubbing, Sherlock can't settle. Jealousy seethes in his stomach, sharp and oily and ugly; it claws at him, forces him to imagine his sister with stange hands and lips all over her, soiling her, touching what is <em>his<em>. When she comes home he can smell the club on her and he refuses to look at her, preferring to sulk in the library, but she wipes off her makeup and kicks off her heels and pads silently over the plush carpet to slide into the armchair opposite his. Sherlock very pointedly does not watch as she unbuttons her blouse and tugs it aside, revealing the nursing bra she has worn all day. His attention is attracted when she unhooks the cup and exposes her nipple, and he sees a pearly drop of milk forming on her. He looks up at her uncertainly.

"Did you really think I'd let anyone else have my milk?" she chides him softly. "You know it belongs to you."

He is on her in seconds, whimpering in her lap as he suckles desperately.

* * *

><p>Soon enough he realises that he, too, is reacting differently when he suckles. A fizz of anticipation starts low in his belly as Mycroft leads him to their safe places, his spine tingles as she unbuttons her blouse (always a blouse, always such a primly dressed young lady) and he starts to want to touch and kiss her nipples and breasts in a way he didn't before. It takes him a while to work out what he is feeling; when he does, he instantly resolves to ignore it. Surely Mycroft would be disgusted that he feels this way. He grows bolder, lapping gently at her breasts with his tongue before latching on, gingerly reaching out for the other before he has finished with the first and squeezing rhythmically, feeling the shape and pliancy and weight of her. He is too turned on to notice the almost imperceptible shift as she parts her legs just a fraction.<p>

Alone in his bed at night he fists his cock desperately, groaning and biting the pillow as he imagines sinking into his sister's warm, welcoming heat. It's all he can ever think of when he is aroused; Mycroft, her lovely face, her trim figure, her ripe milky breasts, the curve of her hips.

Her hand on his erection, even through his boxers, is nearly enough to make him come on the spot.

* * *

><p>The first time he takes her, he is overwhelmed. The welcome, the promise of love, her warmth... he is still slightly drunk on her milk and he thrusts with abandon, lacking all finesse, needing in that moment to fill her, to fall apart in her arms and trust her to catch him. She does not disappoint him.<p>

* * *

><p>Sherlock never thinks about the time she left for London. He can't. He won't. It is too painful. He never knows that Mycroft had wanted him to go with her, had been preparing to take him away; his world had crumbled, and he sought swift and sweet oblivion. He refuses to think about the way she found him in rehab. They both know they can never be apart again, and it shocks both of them to think that they had only been separated eight weeks by the time Sherlock was forced into rehab.<p>

* * *

><p>When Mycroft pushes his son into the world, Sherlock thinks his heart might burst with love for them both. In the weeks following, he attends to her every need, doing everything for her, getting up in the night to change and feed the baby. Mycroft rewards him the only way she knows how, with milk. They are both stupidly happy with his arrangement.<p>

When Leopold is six months old, Sherlock whisks them off back to Switzerland; nobody knows them here, even in Geneva they can walk the streets with their son, holding hands and kissing as they please. They rent a small chateau by a lake and are immensely pleased with the housekeeper; Frau Hudson had married an Englishman long ago, but after being widowed had returned to her homeland, retaining only the knowledge of the ruthlessly efficient running of a proper British household and a small bone china teapot. Leopold takes to her instantly and is happy to be bounced on her knee and fussed over.

On the fourth night of their holiday, when Mycroft has finished feeding their son and he is dozing against her chest, Sherlock crawls onto the bed and takes them both in his arms. "I love you, Mycroft," he whispers huskily, his voice laced with promise. "I love what we have."

"As do I, my darling," she returns tenderly, rewarding him with an open, genuine smile.

"We could do this. Stay here, I mean. You could work from Geneva, I can work anywhere. Leo could grow up speaking French, German and Italian as well as English. Nobody knows us here, we could..." He pauses nervously as he fishes in his pocket. "We could get married," he finishes, producing an antique Victorian gold and diamond ring, his voice betraying his anxiety.

Mycroft gasps softly. "Oh, Lockie," she croons, twisting to kiss him full on the mouth. "_Yes._"


	3. Chapter 3

When Mycroft is fifteen, she realises that she _likes_ feeding Sherlock in more ways than one. Her heartbeat rises and her panties get wet when her sweet little boy kneads and sucks her breasts, when he gets home from school and climbs into her lap and begs in a whisper "_Please can I have some milk, Mummy?_", when he sighs happily after he has drunk his fill. She loves how much he adores her, how he needs her. An odd sense of pride fills her when she thinks that only the promise of being on her breast can calm him. Their real mother has no claim on him, Mycroft thinks fiercely, he is _hers._ Her baby.

She has allowed him the comfort of calling her Mummy since he was four, but she has never used the title to refer to herself except to reassure him that she loves him or missed him while he was at school. Now, though, she begins to think that should change.

Summer has come, and Sherlock has the run of the grounds during the holidays. No longer tied to a schedule he explores gleefully, splashing in the stream and collecting particular stones that strike his fancy, hoarding them under his bed. Mycroft's breasts had swollen with more milk to keep up with the demand of feeding her brother three times a day, but now that he is not subjected to the cruelty of his classmates he does not need the security of nursing in the afternoons; Mycroft, however, does need relief. Her breasts are full and straining and she knows she could buy a pump, but somehow offering her milk to Sherlock seems more appealing. Their parents have gone to stay in London for a weekend, leaving Mycroft in charge, and the servants have walked into the village for lunch. They won't be back for hours. She slips on a white cotton dress, buttoned all the way up the front, and walks out to the pine-built summer house in the shade of the large oak. She calls Sherlock across and he comes bounding across the lawn like a puppy. She sinks gracefully into the large white basket chair, the doors thrown open to allow the breeze in, and pats her lap. He instantly snuggles up to her.

"You remember Mummy told you how her milk will keep coming as long as you keep feeding?" she croons gently, rubbing his back. Sherlock nods. "The more you drink, the more milk Mummy makes. So now Mummy has enough milk to give you a little feed in the afternoons, just like after school. Would you like some of Mummy's milk now, my sweet one?"

Sherlock's face lights up. "Yes please," he gasps eagerly, shuffling into the correct position. Mycroft unbuttons the front of her dress down to her navel and lets Sherlock pull the fabric to the sides, exposing both of her full, aching breasts. Sherlock squeals in pleasure; he knows what it means when her breasts are heavy like this. Pearls of milk form on the tips of her nipples and Sherlock eagerly takes one into his mouth and sucks, making contented little grunts from time to time. She wraps her arms around him and allows herself to revel in the fact that she is openly breastfeeding her brother on the porch of the summer house, the breeze bringing scents of cut grass and flowers, the heat of the sun bathing them both, the oak tree above them rustling.

"That's it, Lockie. My good little boy, drinking up Mummy's milk... All for you." Sherlock sucks, swallows, pushes at her nipple with his tongue to make sure he's finished every last drop. The sound of her creamy milk going down his throat goes straight to her core, leaves her hot and wet and wanting. "Does my baby want the other one too, hmm?" she murmurs softly, encouraging him across. He accepts it with alacrity, wrapping his arms around Mycroft's waist in a loose hug as he buries his face against her and begins to suck again. The sight of his perfect little lips wrapped around her nipple, his dark curls brushing her chest, the feeling of his mouth suckling insistently and drawing her milk out is almost overwhelming. She responds by covering him in praise, stroking his hair. "Such a good boy for Mummy, my sweet little baby." Sherlock whimpers with joy and suckles harder.

Mycroft does not allow herself to masturbate that night. She isn't ready to cross that line, not yet.

* * *

><p>Sherlock grows utterly dependent on feeding from Mycroft three times a day. For him it is as necessary as air; as certain as the sun will rise he knows he will be allowed to suckle on her breasts. If he thought about it, he'd realise he takes it for granted. He'd also realise he doesn't need it anymore. But he never thinks about it, so the problem never presents itself.<p>

He knows to ask politely; he is never refused. If Mycroft is hesitant (other things to do, busy, not now) he cuddles her and surreptitiously rubs his face against the swell of her cleavage. "Please, Mummy," he'll beg, whining, "you must be so full. Please let me have your milk. I want Mummy's milk... please?" It is done with such an air of innocent desperation that Mycroft cannot resist, even though she knows she is being manipulated. She sends him to one of their safe places and slips away to join him. He groans when she exposes her chest for him and dives in without hesitation.

"Your milk tastes so good, Mummy... so creamy... love suckling from you... love being your baby, Mummy... such good milk..." he whimpers as he sucks, sliding his hand as far as he dares towards her other breast.

Mycroft knows he wants to touch. She hesitates, then cards a hand through his hair. "Do you want to touch Mummy's breasts, baby?" she asks softly, smiling as his embarrassed flush and tentative nod. "It's alright, Lockie. You can touch. Mummy's breasts belong to you, you know that. So full of milk to feed my sweet boy." Sherlock groans and cups her greedily, pinching lightly at her nipple.

After that, he is always touching her while he nurses. She teaches him to milk her with his hands as well as his mouth and their nursing sessions grow longer as Sherlock worships her breasts.

* * *

><p>As Sherlock enters puberty his suckling grows needier and more sensual; his aim is no longer to drink as much of her milk as possible, but rather to suck on his sister's breasts as much as she will allow. His touching grows bolder and he gropes her unashamedly as he nurses; he swirls his tongue decadently around he stiff nipples, pulls off with a wet pop and takes her back into his mouth with a soft groan. It doesn't surprise him that he starts to get an erection as he suckles.<p>

One day when he is thirteen the need to suck on her ripe, round breasts overtakes him and he deliberately spills a beaker of acid in the Chemistry lab just before lunch so she will have to come to the school to talk with his teacher. She stalks into the office without looking at him, pays for the damage and dismisses Professor Moody with an imperious eyebrow. Sherlock suddenly feels stupid.

"Do you want to explain to me what you thought you were doing?" Mycroft asks him coolly.

"I - I wanted to see you," he explains pathetically, "I needed - I need to feed so badly. Please, Mummy... it's all I can think about, I need your milk, I need to suckle on you..."

"And you thought spilling acid everywhere would be a good way to get it?" she responds with a derisive snort. "No, Sherlock. I am not going to feed you now. I do not believe it would be wise to reward you for this behaviour." He is so shocked when she reaches out for him that she is able to tug him across her knee with ease. Mycroft raises her hand and delivers a stinging slap to his plush arse and Sherlock bites his lip against the gasp that wants to come.

"You have been a very naughty little boy, Sherlock," she lilts in a sing-song voice. "Bad little boys don't get Mummy's milk, they get spanked. Mummy is going to spank you until you've learned your lesson." She spanks him again, hard enough to hurt even through his trousers, and his cock twitches, begins to thicken. She keeps a steady metronome of slaps, smirking as she feels his cock harden fully against her thigh, listening to his ragged breathing as she spanks him over and over. "Have you learned your lesson yet, you naughty little boy?" she purrs, spanking him again, keeping up the rhythm.

"Yes, Mummy," Sherlock gasps, and comes in his pants with a desperate little whine.

Mycroft helps him to his feet and walks out of the office without another word.

When he gets home that day she beckons him to her bedroom and sits in their usual chair, inviting him to straddle her. "I didn't hurt you too much earlier, I hope?" she says softly, wrapping her arms lightly around his waist.

"No, Mummy," Sherlock sighs, nuzzling into the crook of her neck.

"That's my good boy," Mycroft purrs, "Mummy wouldn't want to hurt you. But no more stunts like that, alright?" Sherlock nods. "Good boy. Give Mummy a kiss," she requests softly, and he instantly presses a soft, tentative kiss to her lips. She smiles and coos and he kisses her again, wanting more, and before long he has his tongue in her mouth and she is more than a little surprised by his skill. He was always a quick learner. His hands come up to massage her breasts as they kiss and Mycroft feels her nipples stiffen as he touches her. "Time for your milk, now," she murmurs, cradling his head as he latches on.

* * *

><p>Sherlock saunters up behind Mycroft where she is leaning on the kitchen table and grasps her hips, pushing his crotch against her bottom and beginning to roll his hips just a little. She raises an eyebrow. "Should you really be doing that?" she enquires, as if asking about the weather.<p>

"Should you really let your little brother suckle from your tits?" Sherlock counters, his voice a low, filthy rumble. "Should you let me rub your pussy? Should you suck my cock? Should you let me fuck you?"

She merely tuts. "Don't be obtuse. You know I meant _here_." She wiggles her hips and spreads her legs just a fraction to give him better leverage, drawing a groan from her brother.

He slides his hands up to grope her breasts, thrusting harder against her, letting her feel his pulsing erection. "Don't care," he grunts obstinately, panting a little. "God, Mycroft, you're so sexy. Fuck." He scrabbles desperately with his zip, freeing his cock, and pushes her skirt up over her hips. Before she can protest he is pushing inside her and thrusting with enthusiasm into her. "Ngh, _oh_, Mycroft... so good..."

Mycroft moans generously. Sherlock's cock is big, there's no denying it, and the delicious stretch as it fills her is exquisite; she knows he isn't wearing a condom, he never has, and the knowledge that he's going to fill her with his semen somehow makes everything even hotter.

"Oh, _Sherlock_," she whines, "yes, oh, yes..." She squeals as he fumbles with her buttons and opens her blouse, milking her with his hands like she'd taught him. The intimacy of that act spurs her arousal and she feels herself growing wetter, feels the easier slide of her brother's cock pounding her. It doesn't take her long to reach her peak and that tips Sherlock over the edge too; he slams in deep and groans long and loud as he spurts wave after wave of his seed into her.

* * *

><p>Their morning feeds somehow retain the innocence of childhood; Sherlock curls up against Mycroft, soft and sleepy, and suckles happily, thinking of the milk as his breakfast. They cuddle and murmur endearments, but neither of them feels particularly sexual during it.<p>

The week after Sherlock fucked her across the kitchen table Mycroft gets her revenge. She waits until bedtime and has him sit up against the headboard; she straddles him and rubs against him until he hardens, then sinks onto his cock with a satisfied moan. He grips her hips, ready to fuck her properly, but she tuts and moves his hands to her breasts, helping him expose her. She arches her back, pushing her breasts closer to his face, until they are all he can see; swollen and milk-heavy and begging for relief.

"No, baby, it's time for your milk," she purrs in his ear, "Mummy needs you to suckle her. Go ahead Lockie, suck Mummy's tits." She undulates her hips, riding him slowly, gently rising and falling, humming at the sensations of his cock moving in her. Sherlock whines in shock and lust as he latches on and suckles, keening when Mycroft rewards him with a squeeze of her internal muscles. She cradles his head, holding him to her breast, and begins to bounce. "That's my sweet baby boy," she breathed, "my perfect little Lockie. Mummy's milk tastes good, doesn't it baby? But you'd still love sucking Mummy's tits even if you didn't get any milk. You love owning Mummy's ripe, milky breasts, don't you baby?"

Sherlock is so turned on he can hardly see. He suckles blindly, whimpering and pushing his face against her, unable to stop his hips from thrusting as his sister rides him. Her words go straight to his cock - she's right, of course - and he forces himself to open his eyes, to see Mycroft astride him, the neckline of her nightgown pulled low to expose her breasts, the hem of it hiked up around her hips. Her breasts are _perfect_, large and heavy and swollen with milk, and he knows he won't last long.

"That's it, Lockie, drink Mummy's milk," Mycroft sighs as she rides him a little faster, "oh my... you're so hungry for it, aren't you? Such a greedy baby boy, feeding so eagerly from Mummy's breasts... Hmm, you've already been fed twice today and still so eager... Good boy Lockie." She purred and rolled her hips, helping him latch on to her other breast and stroking his curls. "Oh, yes, Mummy likes it when her sweet little baby sucks her tits."

Sherlock comes so hard he nearly passes out.

* * *

><p>"I want to give you another baby," Sherlock whispers, kissing Mycroft's neck. "I don't want Leo to be an only child, and I don't think you do either. We're not struggling for money. This feels like a good time to have another child... think about it, will you?"<p>

Mycroft hums. "I'd like that. I'll talk to the clinic."

"No, I -" Sherlock bites his lip. "I want to do it naturally this time."

"You - but surely you understand - the risks would be -" she splutters, not knowing what to think. "There is a very real possibility that the child would be mentally or physically disabled. That's why I went through IVF last time, to make sure we had a healthy baby."

"I know, I just - I want to give you a baby properly. I want to fuck you and come inside you, I want to fill you with my seed again and again until your body accepts it, I want to watch as your womb swells with the baby I put in you."

Mycroft tilts her head to one side. "And if that baby has developmental issues?"

"We could handle it. It would still be _our baby_, a child we made together, out of love. You know I adore Leo with my whole heart and I wouldn't swap him for anything, but - I'd like to make a baby with you."

Mycroft takes a week to think it over.

"Is everything ready for Thursday?" Sherlock asks her, beaming. They are finally getting married. Completely illegally, of course, but there are advantages to occupying a minor position in the British government. There will be a ceremony, and rings, and vows, and flowers, and cake. That is enough.

"Yes, darling," Mycroft replies, signing another report. "The hotel confirmed this morning. We'll have the bridal suite all to ourselves for a whole week." Sherlock grins. "Incidentally, I'm due to ovulate the day of our wedding."

Sherlock chokes on his coffee.

* * *

><p>"Oh, oh, <em>fuck,<em> Mycroft... oh yes, ngh..." Sherlock moans deeply, thrusting with abandon into his sister, stroking her hair out of her eyes. She wraps her legs around his waist.

"Do it, Sherlock... please, please come inside me," she begs with a strange desperation, "fill me up. Give me a baby."

"I will," Sherlock growls, pounding his wife harder. "Oh, _fuck_..." With a strangled shout he is coming, harder than he has ever come in his life. He has deliberately refrained from orgasm for three days, wanting to make sure he has plenty of semen to fill Mycroft with, and he collapses on top of her as his cock pulses again and again, emptying his balls into her. Mycroft screams with her orgasm.

* * *

><p>"Help me with this table, would you?" Sherlock asks Frau Hudson, carrying it into the garden and settling it beside the others. Before long it has been covered in a pristine white tablecloth and laden with food, a jug of Pimms standing neatly to one side.<p>

An hour later the party is in full swing. Leo dashes out of the house wearing a cowboy hat and dives behind Sherlock's legs, giggling. Julian trots after him, sporting a feather headdress and a tiny plastic bow and arrow, and they chase each other in circles around their father until he is dizzy. He sweeps them both up into his arms and covers them both in kisses, making them shriek and wriggle, before releasing them. They charge off together and join the other children, who have come with their parents to celebrate Sherlock's thirtieth birthday, and Mycroft smiles at the sight. She waddles out of the house, enormous with child and balancing Louisa carefully on one hip.

Sherlock swells with pride at the sight of her, his beautiful wife, so hugely pregnant and carrying their perfect little daughter, who is all of two years old and already exhibiting a sharp Holmes mind. She sinks into a chair and holds court with the other wives while Sherlock and the other men talk and laugh.

"I feel bad for your wife," one of his friends says casually, "it can't be easy being eight months pregnant in the middle of summer. Penelope had Xander last August and she really suffered with the heat."

"Yes, I admit Mycroft has found it difficult to cope on occasion," Sherlock smiles softly, "but twins usually do come early, so we live in hope that it won't be too much longer."

* * *

><p>"It's incredible," Mycroft whispered to Sherlock, "by rights, we shouln't have been this lucky." In their cots the twins flailed their limbs and yawned, Anthony reaching out his tiny hand and clasping Marianne's fist.<p>

Sherlock responded with a kiss to her cheek. "Sometimes I can scarcely believe it either. All five of our children are just _perfect_ in every way."

"Perfect. Happy, and healthy, and _perfect,_" she agreed, stroking Sherlock's hand with her thumb. "I did wonder at times if any of them would have inherited your unwillingness to give up breastfeeding, but so far they've all weaned themselves before the age of two without encouragement," she added slyly.

Sherlock grinned, and kissed her to shut her up.


End file.
